My daughter's gerbil chews up his plastic toys in no time. Is this harmful? And can we offer him something else to munch on instead?

J.L., Donna, Texas

Gerbils are little gnawing machines who chomp on everything around them — plastic, wood, cardboard, cloth. This is not about nourishment. When your pet chews his toys, he's accomplishing two things he's programmed to do: producing a fine, soft substance to use for bedding, and wearing down his front teeth (rodents' central incisors grow throughout their life, and gnawing on things keeps them at the proper length).

Because gerbils may accidentally ingest plastic while nibbling toys, some owners opt for chewables that aren't likely to irritate or harm their animals' stomachs. Untreated wood toys are just as satisfying as plastic, and most pet stores carry them. But if you really want to make your little guy's day, give him a few sheets of toilet paper and the empty roll they came on. He'll play in the tube, then gnaw it and the paper into fluff. You'll have a happy, healthy pet — and one who recycles.